Spar, also the president of Barnard College, describes the modern woman's dilemma:

We have opportunities today — to choose our educations, careers, spouses — that would've stunned our grandmothers. But now we're dazed and confused by all the choices.

Feminism was meant to remove a fixed set of expectations; instead, we now interpret it as a route to personal perfection. Because we can do anything, we feel as if we have to do everything.

The problem is that unrealistic expectations cause many successful women to feel guilty for not doing even more. After all, the pursuit of perfection goes far beyond the professional realm for women.

Society places ever more pressure on women today to look beautiful all the time. "Americans, mostly women, spent more than $13 billion on plastic surgery in 2007; 10 million U.S. girls a year have eating disorders; and any magazine rack confirms our obsession with one scantily-clad celebrity after another," Spar writes.

Then, there's the idea of the perfect marriage. No, it's not just about finding a life partner and settling down. "It's all about fireworks, co-parenting, lifelong romance, and ecstatic sex," Spar writes. The problem is, no one ever talks about how hard they have to work on their sex lives and partners in the hopes that it will get on a life-long path. It doesn't just happen overnight, but we somehow still think it does.

All the while, women still feel like they should be perfect mothers. "We want to be fully involved in our children's care — without compromising time at work, with spouses, and for ourselves," Spar writes.

Instead of trying to do everything, women — and men for that matter — should figure out what matters to them and let the other stuff go.

As Spar wrote last year in The Daily Beast: "The challenge lies in recognizing that having choices carries the responsibility to make them wisely, striving not for perfection or the ephemeral all, but for lives and loves that matter."